As fiber-optic system research and use increase, there has been growing interest in developing fiber-based technology for switching, modulation, and system control. Magneto-optic (MO) fiber-based switches have been proposed and studied due to their low insertion loss, possibilities to be integrated into optical systems, large optical cross section (i.e. a majority of the fiber energy is captured by the MO), and the nonreciprocity of the induced polarization rotation due to the Faraday effect. Also, unlike electro-optic or MEMS which can have problems when switching high-power beams due to heat, magneto-optic can handle more power and maintain its switching integrity. These qualities also make MO materials attractive for use in optical modulators. In addition, recent fabrication and control advances of bismuth-substituted iron garnet single domain arrays, growth techniques, and optical circuit integration show promising results for use of magneto-optic materials in integrated high speed systems. In addition, optical switching with MO materials can be achieved with low operating voltages and is polarization independent.
In the non-magneto-optic realm, there has been work on optical modulators and switches using Sagnac and Mach-Zehnder interferometers. A Sagnac interferometer is a closed loop interferometer. The Sagnac interferometer was originally used by Georges Sagnac in 1913 to test for the existence of “luminiferous ether” via an effect now named the Sagnac effect. Though the interferometer is often associated with the Sagnac effect, it has many applications independent of its original application. With the development of optical fiber and fiber optic couplers, a new generation of Sagnac devices has been created, primarily as resonators, sensors, and gyroscopes.
Traditionally, switching time of magneto-optic switches has been slow, in the hundreds of microseconds range. However, with the availability of optics-grade orthoferrites, the switching time of magneto-optic devices can be greatly reduced. Additional improvements in switching speed can be obtained by using domain wall motion for the switching mechanism. In addition to advances in magneto-optic switching time, recent advances in fabrication of magneto-optic materials, growth techniques, optical circuit integration, and the experimental realization of magneto-optical photonic crystals show promising results for use of magneto-optic materials in integrated high speed systems.
Embodiments of the invention provide improved drive circuitry for an optical switch using the benefits provided by a Sagnac interferometer with the control of a magneto-optic device. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.